class Bar { | |
private Object field; | |
private final Object lock = new Object(); | |
public void main() { | |
synchronized (lock) { | |
if (field != null) { | |
return; | |
} | |
} | |
synchronized (lock) { | |
if (field != null) { | |
return; | |
} | |
if (field == null) { | |
System.out.println(); | |
} | |
} | |
} | |
} |